'Mulberry trees' in the Bible

So David enquired of Yahweh, and he said - Thou shalt not go up, - Get round behind them, and come in upon them, over against the mulberry-trees.

And it shall be, when thou shalt hear a sound of marching in the tops of the mulberry-trees, then, shalt thou act with decision, - for, then, will Yahweh have gone forth before thee, to smite the host of the Philistines.